Tubular monofilament fiber

ABSTRACT

A tubular monofilament fiber with predefined weak points for an artificial turf system is disclosed. The fiber comprises a tube comprising a perimeter wall enclosing a hollow interior area of the tube, and a plurality of predefined weak points formed in the perimeter wall that divide the perimeter wall into a plurality of fibrils and connect adjacent fibrils. The predefined weak points are easily breakable to disconnect the plurality of fibrils from each other by mechanical means for brushing the fiber, by conventional brushing processes using in installing an artificial turf, or by footsteps of players. The hollow interior area, the perimeter wall, and the plurality weak points extend from a top end of the fiber to a bottom end of the fiber.

PRIORITY CLAIM

This application claims priority to U.S. Provisional Application 62/063,342, filed Oct. 13, 2014, and U.S. Provisional Application 62/075,132, filed Nov. 4, 2014. The entirety of both applications are incorporated herein by reference.

FIELD OF THE INVENTION

The embodiments of the present invention relate to a monofilament fiber for an artificial turf system. More particularly, the embodiments relate to a tubular monofilament fiber with predefined weak points for an artificial turf system.

BACKGROUND OF THE INVENTION

Artificial turf has been used for years to provide a surface that simulates natural grass. Artificial turf has many benefits over natural grass and, in addition, can be installed and used in places that do not allow for natural grass fields.

One type of artificial turf that is commonly used is an in-filled synthetic grass field. The in-filled synthetic grass field includes a plurality of fibers (also referred to as filaments or ribbons), wherein the fibers are operatively attached to a backing member. Typically the fibers are tufted through the backing member. In most instances, once the backing member (with fibers) is installed on a substrate or other supporting surface, an infill material (typically, rubber, sand or a mixture thereof) is installed to support the fibers in an upright position.

Ideally, the fiber should simulate the look of natural grass, reduce infill mobility, have good rigidity and resilience, have optimal ball-surface and player-surface interaction, and provide excellent tuft retention. Although fibers with various shapes and geometries have been adopted in the past to try to achieve these goals, they are still inadequate. As such, there still remains a need for an improved fiber that exhibits at least some of the above desired characteristics.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, an artificial grass monofilament fiber is described. The artificial grass monofilament fiber comprising a tube comprising a perimeter wall enclosing a hollow interior area of the tube; a plurality of predefined weak points formed in the perimeter wall that divide the perimeter wall into a plurality of fibrils and connect adjacent fibrils, the predefined weak points are breakable to disconnect the plurality of fibrils from each other by mechanical means for brushing the fiber or by footsteps of players; and the perimeter wall and the plurality of predefined weak points extend from a top end of the fiber to a bottom end of the fiber.

An artificial turf system comprising artificial grass monofilament fibers of the above embodiment is also contemplated. In this system, the artificial grass monofilament fibers are tufted through a backing member and infill are disposed on the backing member between the artificial grass monofilament fibers

In one variation of the above embodiment, the perimeter wall has a width between an inner surface of the perimeter wall that is closer to the hollow interior area and an outer surface of the perimeter wall that is farther from the hollow interior area.

In a further variation of the above embodiment, the predefined weak points are closer to the inner surface of the perimeter wall than the outer surface of the perimeter wall.

In a further variation of the above embodiment, the fibrils have a width equal to the width of the perimeter wall.

In a further variation of the above embodiment, the predefined weak points have a width smaller than the width of fibrils.

In one variation of the above embodiment, the predefined weak points have a width smaller than a width of the fibrils.

In one variation of the above embodiment, each of the plurality of fibrils has a diamond shape from a top view or from a cross-sectional view.

In one variation of the above embodiment, each of the plurality of fibrils has a triangle shape from a top view or from a cross-sectional view.

In one variation of the above embodiment, each of the plurality of fibrils has an L-shape from a top view or from a cross-sectional view.

In one variation of the above embodiment, each of the plurality of fibrils has a trapezoid shape from a top view or from a cross-sectional view.

In one variation of the above embodiment, each of the plurality of fibrils has a cross shape from a top view or from a cross-sectional view.

In one variation of the above embodiment, each of the plurality of predefined weak points has a center with a reduced thickness compared to side surfaces of the each predefined weak point contacting the fibrils.

In accordance with another embodiment of the present invention, an artificial grass monofilament fiber is described. The artificial grass monofilament fiber comprising a tube comprising a perimeter wall and a hollow interior area, which forms an enclosure around the hollow area, wherein the perimeter wall includes plural weak points and a slit formed in the perimeter wall that together divides the perimeter wall into a plurality of fibrils, wherein the predefined weak points connect adjacent fibrils and the predefined weak points are each breakable to disconnect the plurality of fibrils from each other by a threshold level of mechanical force comprising a corresponding level of force from brushing the fiber or by footsteps of players, and the perimeter wall and the predefined weak points extend from a top end of the fiber to a bottom end of the fiber.

In one variation of the another embodiment, the fiber has a portion extending above an infill and remaining portion buried in the infill when the infill is applied to the fiber, the fibrils are disconnected from each other in the portion extending above the infill via the predefined weak points by the threshold level of mechanical force.

In a further variation of the another embodiment, the fibrils are connected to each other in the remaining portion buried within the infill via the predefined weak point.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1(a)-(c) illustrate one embodiment of a tubular monofilament fiber with predefined weak points before and after the fibrils extending above the infill are disconnected from each other.

FIG. 2 illustrates a second embodiment of a tubular monofilament fiber with predefined weak points.

FIG. 3 illustrates a third embodiment of a tubular monofilament fiber with predefined weak points

FIGS. 4(a)-4(d) illustrate one embodiment of a spinneret for manufacturing the second embodiment of a tubular monofilament fiber with predefined weak points.

FIG. 5 illustrates the preferred relationships between the weight of the tubular monofilament fiber and the thickness and width of the tubular monofilament fiber.

FIG. 6 illustrates a fibril having a diamond shape from a top view or a cross-sectional view.

FIG. 7 illustrates a fibril having a triangle or triangle-like shape from a top view or a cross-sectional view.

FIG. 8 illustrates fibrils, from left to right, having an L-shape, a trapezoid shape, and a cross shape from a top view or a cross-sectional view.

DETAILED DESCRIPTION OF THE INVENTION

The embodiments of the present invention relate to a fiber for an artificial turf system. Especially, the embodiments relate to a monofilament fiber for such a system. The monofilament fiber further has a tubular structure that is long, round, and hollow like a tube. The tubular monofilament fiber may also be described as a hollow elongated cylinder. The tubular monofilament fiber includes multiple easily breakable regions that can divide a single fiber into multiple disconnected sub-fibers once these regions are broken. These regions may have any shapes, structures, and dimensions depending on the cross-sectional shape of the fiber, the cross-sectional shape of the sub-fiber, the cross-sectional shape of the hollow portion, the number of sub-fibers, and the material forming the fiber. These regions are easily breakable by mechanical means for brushing an artificial turf, by conventional brushing processes used in installing an artificial turf, or by footsteps of players. The tubular monofilament fiber, whether before and after it is broken into multiple sub-fibers, resembles the look of natural grass with the proper amount of light reflection, and provides better fiber support in the infill, reduced infill mobility, enhanced rigidity and resilience, more optimal ball-surface interaction, and improved tuft retention. Details of various embodiments are discussed below.

Now referring to FIGS. 1(a)-(c), one embodiment of a tubular monofilament fiber with predefined weak points is illustrated. FIG. 1(a) shows a monofilament fiber 100 comprising a tube comprising a perimeter wall 110 enclosing a hollow interior area 105 of the tube, and a plurality of predefined weak points 115 formed in the perimeter wall 110. The perimeter wall 110, the hollow interior area 105, and the plurality of predefined weak points 115 extend from a top end 120 of the fiber 100 to a bottom end 125 of the fiber 100.

FIG. 1(b) is a top view of the fiber 100 viewing from the top end 120. This figure may also be a cross-sectional view. Each predefined weak point 115 is formed by a cut 130 into the perimeter wall 110 such that the width of the perimeter wall 110 is substantially reduced. The term “cut” is being used to refer to the illustrated indentation, narrowing, a “cut out” portion in the perimeter wall, recess, or reduction in dimension. The width of the perimeter wall 110 is the distance between an inner surface of the perimeter wall 110, which is closer to the hollow interior area 105, and an outer surface of the perimeter wall 110, which is farther from the hollow interior area 105. The cut 130 also renders the predefined weak points 115 to be closer to the inner surface of the perimeter wall 110 than the outer surface of the perimeter wall 110. In addition, the cut 130 divides the perimeter wall 110 into a plurality of fibrils 135 that are weakly connected to each other through the predefined weak points 115. “Weakly connected” means that each predefined weak point has a connection strength easily breakable by mechanical means for brushing an artificial turf or by conventional brushing processes used in installing an artificial turf, i.e., beating or fibrillating the weakly connected fibrils to split the fibrils, or by footsteps of players but have a strength sufficient to maintain their integrity or connection during prior handling such as tufting the fiber into a backing. The mechanical means exerts enough force to break the connected fibrils and is below the force that would damage the fibril such as chipping or severing the fibril. The width of each fibril 135 is larger than the width of each predefined weak point 115 since the width of each fibril 135 is essentially the width of the perimeter wall 110 and the width of each predefined weak point 115 is a reduced width of the perimeter wall 110. The fibrils 135 and predefined weak points 115 are continuously and integrally formed using the same material, as seen in perspective view (FIG. 1(a)) and in top/cross-sectional view (FIG. 1(b)). FIGS. 1(a) and 1(b) show a tubular monofilament fiber before it is “broken” or before the fibrils 135 are separated from each other.

The fibrils 135 are separated from each other when the fiber is brushed by a mechanical means for brushing or grooming an artificial turf or by a conventional process used in installing an artificial turf such as fibrillation, when a force exerted on the predefined weak points 115 is equal to the brushing force of the mechanical means or the fibrillation, or when accumulation of force exerted on the predefined weak points 115 is equal to the brushing force of the mechanical means or the fibrillation. All these force are below the force that would damage the fibrils 135, and the latter two forces may be generated by the footsteps of players. FIG. 1(c) is an example after the tubular monofilament fiber 100 is “broken” or after the fibrils 135 are separated from each other. This figure depicts a fiber 100 after infill 140 is applied to the fiber 100 such that the fiber 100 has a portion extending above the infill 140 and the remaining portion buried in the infill 140, and after the fiber 100 has been brushed or used to a level such that all the fibrils in the portion extending above the infill 140 are disconnected from each other. As a result, a single fiber is broken into multiple sub-fibers. The fibrils 135 in the remaining portion buried in the infill 140, or the fibrils 135 buried in the infill 140, are connected to each other and has an identical configuration as the one shown in FIG. 1(b) when a cross-sectional view is taken from that portion.

In a preferred embodiment, the fiber 100 has a length of approximately 2.5 inch above the backing member (pile height), the portion extending above the infill has a length of approximately 0.75 inch, and the remaining portion buried in the infill has a length of approximately 1.75 inch, which is also the infill height. The fiber 100, however, may also have a pile height such as 2.25 inch, 2 inch, 1.75 inch, or other height depending on the requirement of the sport being played on the fiber 100. Regardless what the pile height is, the infill is applied to the backing member to reach a height such that the portion extending above the infill always has a length of approximately 0.75 inch in this preferred embodiment.

The infill 140 may comprise any number of combinations of conventional particulate material, including hard particles, resilient particles, and combinations thereof. Some typical hard particulate material includes: sand, rock, and hard and heavy plastics; and typical resilient particulate materials can include: used tires made from styrene-butadiene rubber (SBR) (including ambient and cryogenic granulated material), cork, ethylene propylene diene monomer (EPDM) rubber, neoprene and other organic materials.

FIG. 1(c) shows splitting of the fibrils 135 from the top of the fibrils toward the infill 140. The splitting in FIG. 1(c) shows that the fiber 100 is being brushed, used, or worn to a level that has not yet split all the way down to the top of the infill 140. With additional force, the splitting may further extend to the top surface of the infill 140. While not shown in the figure, the splitting may also occur from the bottom of the portion extending above the infill toward the top of the portion extending above the infill.

When a tubular monofilament fiber 100 is installed, for example, with its bottom end 125 tufted into a backing member and buried in the infill 140, the fiber 100 initially has a configuration shown in FIGS. 1(a)-1(b) and described above. After the installed fiber 100 has been brushed, used, or worn to a level, all the fibrils 135 extending above the infill 140 are disconnected from each other. The level of usage or wear that renders the separation of all the fibrils 135 may be a single or accumulation of force. A single force means one single footstep by a player with a force equal to the brushing force of a mechanical means for brushing an artificial turf or fibrillation. Accumulation force means multiple footsteps from a player or multiple players with a total force equal to the brushing force of a mechanical means for brushing an artificial turf or fibrillation. The footsteps may be generated by a player or players walking or running on the field in which the fiber 100 is installed. As such, an artificial turf having tubular monofilament fibers may be brushed prior to any games on the turf to disconnect the fibrils by a mechanical means or be broken during the games by the players. All the fibrils 135 may be disconnected from each other simultaneously or at different times depending on the kind of the sport being played on the fiber 100, the amount of force being exerted on the fiber 100 by the player(s) or mechanical means, or the manner in which the turf is brushed. When the fibrils 135 are disconnected at different times, only a fibril or some fibrils 135 are disconnected, or break away, from the connected fibrils 135 at a time, and additional connected fibrils 135 are broken away some time afterward until all the fibrils 135 are disconnected from each other.

A tubular monofilament fiber with disconnected fibrils extending above the infill provides a better aesthetic, with increased fiber volume and improved plushness. Moreover, when a tubular structured fiber is buried in the infill, its provides better fiber support, reduced infill mobility, enhanced rigidity and resilience, more optimal ball-surface interaction, and improved tuft retention compared to traditional (non-tubular) monofilament fibers.

Although FIGS. 1(a)-1(c) show a tubular monofilament fiber comprising a round/oval hollow interior area, a round/oval perimeter wall, a certain shape of the fibrils and cuts, and a certain number of the fibrils and cuts (5 each in this embodiment), all these area, wall, fibrils, and cuts may have other shapes and quantity as illustrated in the embodiments below.

Referring to FIG. 2, a second embodiment of a tubular monofilament fiber with predefined weak points is illustrated. FIG. 2 shows monofilament fiber 200 comprising a tube comprising a perimeter wall 210 enclosing a hollow interior area 205 of the tube, a plurality of predefined weak points 215 formed in the perimeter wall 210. The perimeter wall 210, the hollow interior area 205, and the plurality of predefined weak points 215 extend from a top end 220 of the fiber 200 to a bottom end 225 of the fiber 200.

In this embodiment, the perimeter wall 210 has a round or ring shape that further includes ripple, ridge, sickle, or crescent shaped inner and outer surfaces 220, 225 similar to FIG. 2 disclosed in application Ser. No. 13/192,004. The inner surface 220 is a surface closer to the hollow interior area 205 and the outer surface 225 is a surface farther from the hollow interior area 204. The plurality of predefined weak points 215 divide the perimeter wall 210 into a plurality of fibrils 230 and allow the plurality of fibrils 230 to be disconnected from each other. The predefined weak points 225 have a center 235 with a reduced thickness (which is the distance B as shown in FIG. 5 that is discussed and defined later, but it is the distance B of the predefined weak points 225) compared to the side surfaces 240 of the predefined weak points 225 contacting the fibrils 230. The perimeter wall 210 is consisted of the plurality of fibrils 230 and the plurality of predefined weak points 215. Although this embodiment shows only four (4) fibrils and four (4) predefined weak points, other numbers such as more or less than four (4) are also contemplated by this embodiment. For example, FIG. 3 shows a top view of another embodiment 300 that has eight (8) fibrils 330 and eight (8) predefined weak points 315. Like FIG. 2, the fiber 300 also has a hollow interior area 305, a perimeter wall 310 enclosing the hollow interior area 305, and similar shaped inner and outer surfaces 320, 325. Moreover, both inner and outer surfaces 320, 325 may have other shapes, and may have the same or different shape from the other inner/outer surface. Both the fibers 200 and 300 have similar physical characteristics as the fiber 100, i.e., adjacent fibrils are weakly connected, and are installed and brushed (or used) in the same manner as described above.

While the predefined weak points of the first and second embodiments have specific structures, shapes, and dimensions, they may be varied depending on the cross-sectional shape of the fiber, the cross-sectional shape of the fibril, the cross-sectional shape of the hollow interior area, the number of fibrils, and the material forming the fiber, and/or to suit the characteristics of the fiber.

FIGS. 4(a)-4(d) show one embodiment of a spinneret 400 for manufacturing the second embodiment of a tubular monofilament fiber with predefined weak points. FIG. 4(a) is a front view of the spinneret 400, FIG. 4(b) is a side view of the spinneret 400, FIG. 4(c) is a rear view of the spinneret 400, and FIG. 4(d) is a cross-sectional view taken from the A-A line in FIG. 4(a). The spinneret 400 comprises clusters of openings 405, and each cluster of openings 405 further comprises a plurality of orifices 410, a plurality of apertures 415 dividing adjacent orifices, and a body 420 enclosed by the orifices 410 and apertures 415. When the material for making a tubular monofilament is extruded through the spinneret 400, the material extruded from each orifice forms a fibril having a shape corresponding to the shape of the orifice and the material extruded simultaneously from each aperture forms a predefined weak point having a shape corresponding to the shape of the aperture. The body 420 is impervious, and the formation of the fibrils and the predefined weak points simultaneously form a hollow interior area that has a shape corresponding to the shape of the body 420. The orifices 410 and the apertures 415 together form a perimeter wall. The material for making a tubular monofilament may be linear low density polyethylene (LLDPE), low density polyethylene (LDPE), polypropylene (PP), thermoplastic polyurethane (TPU), nylon-6 (PA-6), or nylon 6-6 (PA6-6).

Although the second embodiment fiber 200 and the spinneret 400 have specific structures and dimensions, they may be modified to have a different number of fibrils/orifices and predefined weak points/apertures. Moreover, each fibril in the second embodiment fiber 200 may have a thickness between 50-600 microns (the distance from an inner surface of the fibril that is closer to the hollow interior area to an outer surface of the fibril that is farther from the hollow interior area), a weight between 500-3000 decitex, and a width between 0.5-5.0 mm (the distance from one end of the fibril contacting a predefined weak point to another end of the fibril contacting another predefined weak point in a straight line, which is distance A shown in FIG. 5). Preferably, the second embodiment fiber 200 may have specific thickness and width ranges based on the weight of the fibril. The preferred relationships are detailed in FIG. 5.

Referring to FIG. 5, when the fibril has a weight between 500 and 1000 decitex, the width of the fibril, which is distance A, may have a range between 500 and 1000 microns, the thickness of the fibril, which is distance B, may have a range between 50 and 150 microns, the outer diameter of the fiber 200, which is distance C, may have a range between 2500 and 6000 microns, and the inner diameter of the fiber 200, which is distance D, may have a range between 2200 and 5800 microns. When the fibril has a weight between 1500 and 2000 decitex, the width of the fibril may have a range between 800 and 1500 microns, the thickness of the fibril may have a range between 100 and 400 microns, the outer diameter of the fiber 200 may have a range between 6000 and 10000 microns, and the inner diameter of the fiber 200 may have a range between 5500 and 9900 microns. When the fibril has a weight between 2500 and 3000 decitex, the width of the fibril may have a range between 1200 and 3000 microns, the thickness of the fibril may have a range between 200 and 600 microns, the outer diameter of the fiber 200 may have a range between 10000 and 16000 microns, and the inner diameter of the fiber 200 may have a range between 9000 and 15500 microns. The outer diameter of the fiber is the diameter of the fiber measured between the outer surface of the fiber or fibril and the inner diameter of the fiber is the diameter of the fiber measured between the inner surface of the fiber or fibril. The inner diameter of the fiber is also the diameter of the hollow section. Both diameters may be measured between peaks, indentations, or between a peak and an indentation depending on the structure of the fiber or the fibril. In this example, both diameters are measured between peaks. Although distances A and B appear to be the same for each fibril, these distances may also be varied to have fibrils with different dimensions. All of the above relationships may apply to other embodiments as well. The fiber 200 has similar physical characteristics as the fiber 100, i.e., adjacent fibrils are weakly connected, and is installed and brushed (or used) in the same manner as described above.

FIG. 6 illustrates a fibril having a diamond shape from a top view or a cross-sectional view.

FIG. 7 illustrates a fibril having a triangle or a triangle-like shape from a top view or a cross-sectional view.

FIG. 8 illustrates fibrils, from left to right, having an L-shape, a trapezoid shape, and a cross shape from a top view or a cross-sectional view. It is understood that the fibrils are connected by predefined weak points. For example, in the tubular monofilament fiber with L-shaped fibrils, each L-shaped fibril is connected to each adjacent L-shaped fibril via a predefined weak point.

In yet another embodiment of a tubular monofilament fiber, the fiber in the above embodiments may be modified to comprise a perimeter wall, an opening in the perimeter wall, and a hollow interior area surrounded by the perimeter wall and the opening. In a preferred embodiment, the opening has dimensions corresponding to or identical to dimensions of a predefined weak point such that a predefined weak point can fit into that opening. However, dimensions slightly larger or smaller than a predefined weak point are also contemplated by this embodiment. The opening may be formed at a location where a predefined weak point is supposed to be formed or at other locations on the perimeter wall. This embodiment is similar to the above embodiments shown in FIG. 1(b), FIG. 2, and FIG. 3 except that one of the plurality of predefined weak points (115 of FIG. 1(b), 215 of FIG. 2, or 315 of FIG. 3) is replaced with an opening. As such, the opening disconnects adjacent fibrils (before fibrillation) and the perimeter wall does not fully enclose the hollow interior area. This opening in the perimeter wall can facilitate faster breaking of the fibrils.

While this feature of having an opening in the perimeter wall is applied to a fiber with a plurality of predefined weak points in the above illustrations, this feature can also be applied to a fiber that has only one predefined weak point. In that example, the fiber has only one predefined weak point and an opening in the perimeter wall may be broken into two fibrils.

As a matter of production and application, in some embodiments, it may be desired to extrude a fiber that has a perimeter wall that has a slit or very small opening. The perimeter wall can be shaped to form an enclosure and to form a tube as the fiber is extruded. The idea is that the fiber will be extruded with the predefined weak points but it is possible to extrude the fiber with one less weak point by extruding the fiber with a slit, a small gap, at a location where for example a weak point would have been extruded. This can result in a similar structure to where the wall, as formed, is continuous and without breaks because the single break creates only a small structural change in the extruded tuber. For example, the tube can have two predefined weak points and one slit. The predefined weak points (or weak points and slit) are preferably structured and configured to at positions on the cross-sectional view of the fiber where the distance between them can create fibrils having the same or substantially the same dimensions.

Process steps can be implemented in various other orders as would be understood by a person with ordinary skill in the art that elements claimed. Different combinations of features would also be understood to be contemplated even if they are not described together or in the same context. Broader inventions are also contemplated arising from removing or modifying one or more features of described embodiments.

It is to be understood that the embodiments of the present invention described herein may be contemplated by one of ordinary skill in the art and that the scope of the present invention is not limited to the embodiments disclosed. While specific embodiments of the present invention have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying claims. 

1. An artificial grass monofilament fiber comprising: a tube comprising a perimeter wall enclosing a hollow interior area of the tube; a plurality of predefined weak points formed in the perimeter wall that divide the perimeter wall into a plurality of fibrils and connect adjacent fibrils, the predefined weak points are breakable to disconnect the plurality of fibrils from each other by mechanical means for brushing the fiber or by footsteps of players; and the perimeter wall and the plurality of predefined weak points extend from a top end of the fiber to a bottom end of the fiber.
 2. An artificial turf system comprising artificial grass monofilament fibers of claim 1 that are tufted through a backing member and infill that are disposed on the backing member between the artificial grass monofilament fibers.
 3. The fiber according to claim 1, wherein the perimeter wall has a width between an inner surface of the perimeter wall that is closer to the hollow interior area and an outer surface of the perimeter wall that is farther from the hollow interior area.
 4. The fiber according to claim 3, wherein the predefined weak points are closer to the inner surface of the perimeter wall than the outer surface of the perimeter wall.
 5. The fiber according to claim 3, wherein the fibrils have a width equal to the width of the perimeter wall.
 6. The fiber according to claim 3, wherein the predefined weak points have a width smaller than the width of fibrils.
 7. The fiber according to claim 1, wherein the predefined weak points have a width smaller than a width of the fibrils.
 8. The fiber according to claim 1, wherein each of the plurality of fibrils has a diamond shape from a top view or from a cross-sectional view.
 9. The fiber according to claim 1, wherein each of the plurality of fibrils has a triangle shape from a top view or from a cross-sectional view.
 10. The fiber according to claim 1, wherein each of the plurality of fibrils has an L-shape from a top view or from a cross-sectional view.
 11. The fiber according to claim 1, wherein each of the plurality of fibrils has a trapezoid shape from a top view or from a cross-sectional view.
 12. The fiber according to claim 1, where each of the plurality of fibrils has a cross shape from a top view or from a cross-sectional view.
 13. The fiber according to claim 1, wherein each of the plurality of predefined weak points has a center with a reduced thickness compared to side surfaces of the each predefined weak point contacting the fibrils.
 14. An artificial grass monofilament fiber comprising: a tube comprising a perimeter wall and a hollow interior area, which forms an enclosure around the hollow area, wherein the perimeter wall includes plural predefined weak points and a slit formed in the perimeter wall that together divides the perimeter wall into a plurality of fibrils, wherein the predefined weak points connect adjacent fibrils and the predefined weak points are each breakable to disconnect the plurality of fibrils from each other by a threshold level of mechanical force comprising a corresponding level of force from brushing the fiber or by footsteps of players, and the perimeter wall and the predefined weak points extend from a top end of the fiber to a bottom end of the fiber.
 15. The fiber according to claim 14, wherein the fiber has a portion extending above an infill and remaining portion buried in the infill when the infill is applied to the fiber, the fibrils are disconnected from each other in the portion extending above the infill via the predefined weak points by the threshold level of mechanical force.
 16. The fiber according to claim 15, wherein the fibrils are connected to each other in the remaining portion buried within the infill via the predefined weak point. 